Siliconization of glass containers is often a necessary step prior to the packaging of pharmaceutical and cosmetic preparations. A concern when packaging preparations in glass containers, including bottles, injection cartridges, IV infusions, syringes, vials, etc., is that leaching of alkali from the glass components can occur. Sometimes described as “water attack”, leaching can be a concern even for glass recommended for pharmaceutical preparations, viz., glass types I, II, and III. One of the most common causes of leaching is the extreme sterilization conditions that glass containers are generally subjected to prior to filling. Such conditions, for example, autoclaving, that requires heating the containers to about 121° C. using high steam pressure, and “baking” and/or oven sterilization, where glass containers can be subjected to temperatures exceeding 200° C., can result in considerable leaching of components from the glass. In addition, certain preparations, such as, for example, acidic drugs/cosmetics, can also promote leaching from glass. Thus, a common practice is to coat the surface of glass containers with silicone prior to their sterilization and filling. Silicone coating of glass containers, in addition to reducing the leaching of glass components, can also function as lubricants. Thus, a silicone coating can improve the drainage of fluids, and suspensions, especially viscous ones. The use of silicone coatings in containers is common for suspensions of steroids and combinations of penicillin and dihydrosterptomycin. Silicone can also be used in preparations in containers where the contents have high solid content, and formulation modifications cannot improve the drainage of the preparation from the containers. In addition, the inner surfaces of cartridges and syringes can be siliconized to allow free movement of the plunger through the cartridge or syringe. The outside of cartridges and syringes and other glass containers can also be siliconized to ease their transport through the steps in an assembly line, for example, through a sterilization setup. Siliconization typically involves application of, for example, by spraying, the silicone emulsion onto the surface of containers, usually as the last step of the cleaning protocol. After spraying with the emulsion, the containers are heat sterilized, which bakes the silicone oil onto the glass surface.
Several silicone oil-in-water emulsions are commercially available for the purposes of lubrication and siliconization of containers and delivery systems. However, the commercially available silicone oil-in-water emulsions usually contain several additives that may be of concern. The concerns arise because, a) these materials can degrade during heat sterilization, that often use temperatures in excess of 300° C., in the case of baking, and 121° C. with high steam pressure during autoclaving and b) the additives and the degraded components, could effect the stability of the preparation to be filled, and may also be incompatible with the preparations. In particular medicinal preparations, especially those containing peptides, proteins and alkaloids, may be highly susceptible to additives, as well as the degraded components, present in silicone-oil-in-water emulsions, For example, it is recommended that the baking conditions for the commonly used 35% Dimethicone NF emulsion not exceed 200° C. to avoid the possibility of oxidation and formation of formaldehyde. Over-baking an article treated with 35% Dimethicone NF emulsion can result in a cloudy appearance on the surface of the treated article.
U.S. Pat. No. 5,443,760 discloses an oil-in-water emulsion having a low HLB value. The compositions are prepared with silicone-oxyalkylene copolymeric surfactants.
U.S. Pat. No. 6,248,855 discloses a silicone oil-in-water emulsion containing a linear non-cross linked silicone copolymer prepared by polymerizing an OH endblocked polydimethylsiloxane monomer with an amine functional trialkoxysilane monomer in the presence of a metal catalyst. In the process the polymerization is interrupted by phase inversion emulsification of the copolymer, and addition of a carboxylic anhydride to avoid reverse depolymerization.
U.S. Pat. No. 6,300,442 discloses a process for making a cosmetically or pharmaceutically-acceptable emulsion or gel composition in which a reaction mixture comprising a vinyl monomer is heated in an oil solvent, such as silicone oil, in presence of a cross linking agent and an oil soluble surfactant, with agitation, in the presence of an inert gas, at about 40-150° C., followed by addition of water to form an form an oil-in-water, a water-in-oil or a water-in-oil-in-water emulsion or gel.
U.S. Pat. No. 6,784,144 describes a silicone oil emulsion stabilized with soap. The soap includes: one or more carboxylates of a fatty acid having from 8 to 18 carbon atoms; and a cation of a base, the soap being formed in situ from the fatty acid and the base during formation of the emulsion.
Published International Patent Application No. WO 2004/100862 discloses oil and water emulsions comprising silicone oil an electrosteric stabilizer and a polyol and/or hydroxy acid. The electrosteric stabilizer can be a copolymer of polyacrylate and alkylated polyacrylate.
Published International Patent Application No. WO 2005/105024 discloses silicone oil-in-water emulsions that are stabilized by a combination of silicone polyether and anionic surfactants. The resulting oil phase is dispersed in the emulsion as particles having an average size of less than 5 micrometers (μM).
Published International Patent Application No. WO 2003/011948 discloses emulsions of water, a volatile siloxane, long chain or high molecular weight silicone polyether, an optional co-surfactant such as, a monohydroxy alcohol, organic diol, an organic triol, an organic tetraol, a silicone diol, a silicone triol, a silicone tetraol and a nonionic organic surfactant.
Published International Patent Application No. WO 2003/064500 discloses compositions of silicone oil-in-water emulsions, having silicone polyethers that are stable in the presence of salts, alcohols and organic solvents. The silicone polyether can be the only emulsifier or in can be used in combination with other organic type surfactants.
Thus, there is a need for stable silicone oil-in-water emulsions wherein the emulsion is substantially free of any additives. In particular, there is a need for silicone oil-in-water emulsions, substantially free of any additives that are stable for an extended period of time.